Adjustable potentiometer



Feb. 24, 1970 L, W, SCHEEL 3,497,856

I ADJUSTABLE POTENTIOMETER Filed Sept. 20. 1967 2, Sheets-Sheet 1 0a/5 MScHffL 5 Feb. 24, 1910 L. w. SCHEEL 3,497,856

ADJUSTABLE POTENTIOMETER Filed Sept. 20. 1967 2 Sheets-Sheet 2 0a/5 k/.56h/51. Mg. 5 5V United States Patent O M' 3,497,856 ADJUSTABLEPOTENTIOMETER Louis W. Scheel, Columbus, Nebr., assignor to DaleElectronics Inc., Columbus, Nebr., a corporation of Nebraska Filed Sept.20, 1967, Ser. No. 669,201 Int. Cl. H01c 5/02, 5/00 U.S. Cl. 338-162 5Claims ABSTRACT F THE DISCLGSURE An adjustable trimmer potentiometerhaving a lgear in engagement with an adjusting leadscrew, the gear beingoperatively connected to a wiper arm assembly which slidably engages theresistance element. The gear includes peripheral teeth extendingtherefrom which engage the threads of the leadscrew whereby rotation ofthe leadscrew will rotate the gear and hence the Wiper. The gear and itsteeth are somewhat liexible to permit the deection or ratcheting of theteeth over the threads of the leadscrew when the wiper arm assemblyreaches the limits of its travel to prevent damage to the unit.

A problem encountered in the fabrication and use of trimmerpotentiometers utilizing an adjusting leadscrew is the damage resultingfrom adjusting the unit beyond its lixed limits. Thus, when the wiperarms reaches the limits of its travel, the unit is damaged uponcontinued rotation of the leadscrew.

Therefore, a principal object of this invention is to provide anadjustable potentiometer that will not have its internal parts damagedby adjustment beyond`ts design capabilities.

A further object of this invention is to provide an adjustablepotentiometer having a exible gear in engagement with the leadscrew, thegear adapted to ratchet over the threads of the leadscrew when the wiperarm assembly reaches the limits of its travel.

A further object of this invention is to provide an adjustable trimmerpotentiometer which is easily fabricated.

A further object of this invention is to provide an adjustablepotentiometer of the trimmer type which is easily assembled.

A further object of this invention is to provide an adjustablepotentiometer having mean's for generating sufficient leadscrew torqueso that the potentiometer will maintain its position of adjustment.

A further object of this invention is to provide an adjustablepotentiometer that will have a long operating life.

A further object of this invention is to provide an adjustablepotentiometer which is economical of manufacture, durable in use andrefined in appearance.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, andcombination of the various parts of the device, whereby the `objectscontemplated are attained as hereinafter more fully set forth,specifically pointed out in the claims, and illustrated in theaccompanying drawings in Which:

FIG. 1 is a top perspective view of the potentiometer;

FIG. 2 is an enlarged sectional view of the potentiometer as seen alonglines 2 2 of FIG. 1;

FIG. 3 is an exploded perspective view of the potentiometer;

FIG. 4 is a sectional View of the potentiometer as seen along line `4 4of FIG. 2 with portions thereof cut away to more fully illustrate theinvention; and

3,497,856 Patented Feb. 24, 1970 ICC FIG. 5 is a sectional view as seenalong lines 5-5 of FIG. 2 with portions thereof cut away to more fullyillustrate the invention.

The potentiometer of this invention is generally designated by thereference numeral 10 and includes an upper case 11 and a lower case 13which are bonded together by any convenient means. Case 13 is providedwith an upstanding shoulder 15 extending therearound inwardly of itsperiphery as best seen in FIG. 3. Case 13 is provided with a circularcompartment 17 which extends around an upstanding post portion 19. Postportion 19 has a reduced diameter portion 21 at its upper end therebydefining a shoulder 23 therebetween. As seen in FIG. 3, post portion 19is provided with a pair of cut away areas 25 and 27 on opposite sidesthereof. Shoulder 15 has three notches 29, 31 and 33 formed thereinwhich are adapted to receive leads 35, 37 and 39 respectively.

The numeral 41 generally designates a circular resistance coil which iscomprised of a core 43 and windings 45. Coil 41 is mounted in thecircular compartment 17 of lower case 13 by any suitable means. Theopposite ends 47 and 49 of coil 41 terminate in spaced relationshipwithin compartment 17 of lower case 13. Terminal connecting elements 51and 53 are secured to the lower surfaces of the opposite end portions ofcoil 41 and the insulated leads 35 and 37 are connected to the elements51 and 53 respectively.

A collector 55 is mounted on reduced diameter portion 21 and has adownwardly extending tab 57 received by cut away area 25. Collector 55also has a downwardly extending tab 59 which is received by cut awayarea 27. Tab 59 includes a horizontal portion 61 which is secured to theunder side of lead 37. The numeral 63 designates a tab which extendsradially outwardly from collector 55 as best illustrated in FIG. 3. Awiper 65 is mounted on reduced diameter portion 21 above collector 55and has a pair of upwardly extending tabs 67 and 69 provided thereon. Asseen in FIG. 3, wiper is provided with a resistance coil engagingportion 71 which is arcuate in cross-section and which is designed towipe upon the resistance coil 41. The other end of wiper 65 is providedwith a downwardly extending tab 73 which is adapted to engage tab 63 tolimit the travel of the wiper.

A drive coupler 75 is mounted on the upper portion of wiper 65 androtatably embraces a portion of the reduced diameter portion 21 as seenin FIG. 2. Drive coupler 75 has a central opening 77 which embraces thereduced diameter portion 21 and has a pair of openings 79 and S1extending vertically therethrough as best illustrated in FIG. 3'. Asalso illustrated in FIG. 3, drive coupler 75 is provided with threeslots 83, 85 and 87 formed in its peripheral flange 89. The openings 79and 81 in drive coupler 75 are adapted to receive the upwardly extendingtabs 67 and 69 of wiper 65 so that wiper 65 will be rotated uponrotation being imparted to drive coupler 75.

Case 11 includes a downwardly extending central post portion 91 which isadapted to be positioned directly over reduced diameter portion 21 asillustrated in FIG. 2. The lower peripheral edge 93 of case 11 isadapted to be received on the upper end of case 13 as illustrated inFIG. 2 and would be secured thereto by any convenient bonding method.The numeral 95 designates a flexible gear having a central opening 97through which post 91 extends. Gear 95 has three tabs 99, 101 and 103extending downwardly therefrom which are received by slots 83, S5 and 97respectively in drive coupler 75. Gear 95 has a plurality of peripheralteeth extending outwardly and downwardly therefrom as illustrated inFIGS. l2 and 3. Spring 107 is mounted on post 91 between gear 95 and theupper surface of drive coupler 75 as illustrated in FIG. 2.

A leadscrew 109 is rotatably mounted in case 11 in a manner best seen inFIG. 4. The leadscrew includes an inner end 111 which is journalled in abore 113 formed in case 11 and a slotted outer end 115. An O-ring 117embraces leadscrew 109 adjacent the outer surface of case member 11 toprevent foreign material from entering the interior of the unit.Leadscrew 109 is maintained within case 11 by a rolled or spiraledspring 119 which extends thereinto and which is received by an annulargroove 121 in the leadscrew. Spring 119 is compressed as it is insertedinto the potentiometer and thereby causes drag to be applied to thegroove 121 of the leadscrew. This drag generates suicient leadscrewtorque so that the potentiometer will maintain its position ofadjustment. Leadscrew 109 is also provided with a threaded portion 123including a plurality of threads 125. As seen in FIG. 4, the teeth 105of gear 95 are in mesh with the threads v 125 on leadscrew 109.

In operation, the leadscrew 109 may be rotated to adjust thepotentiometer by use of a conventional screw driver. The rotation ofleadscrew 109 will cause gear 95 to be `rotated due to the engagement ofteeth 105 with the threads 125. The rotation of gear 95 causes drivecoupler 75 and wiper 65 to be rotated therewith due to the connectionthereof as previously described. The wiper 65 is thereupon moved overthe top surface of resistance coil 41 so that the resistance in theelectrical circuit can be selectively varied in conventional fashion.When the wiper 65 has reached the limits of its travel with respect tothe resistance coil 41, the continued rotation of leadscrew 109 willcause the ratcheting of the teeth 105 with respect to the threads 125.The `flexible characteristics and design of the gear is such that theteeth 105 will be deflected upwardly or ride over the threads upon thecontinued rotation of the leadscrew 109 to provide a ratcheting eifect.Thus, the internal components of the unit will not be damaged due tocontinued rotation of the leadscrew since the teeth 105 will ratchetwhich means that gear 95, drive coupler 75 and wiper 65 will not berotated. It can be appreciated that the teeth 105 can be indefinitelyratcheted with respect to the leadscrew without causing damage to eitherof the leadscrew or gear 95. It should also Ibe understood that not onlydo teeth 105 deflect upwardly but a portion of the outer end of gear 95adjacent thereto also is dellected slightly upwardly during theratcheting phenomena. Thus, it can be seen that an adjustablepotentiometer has been provided which will not have its parts damaged byadjust-ment beyond its `designed capabilities.

The -components of the unit are constructed of conventional materialswhile gear 95 is preferably constructed of #25 Berylco.

Thus, it can be seen that the device accomplishes at least all of itsstated objectives.

Some changes may be made in the construction and arrangement of myadjustable potentiometer without departing from the real spiritand`purpose of my invention, and it is my intention to cover by myclaims, any modified forms `of structure or use of mechanicalequivalents which may be reasonably included within their scope.

I claim:

1. In an adjustable potentiometer,

a housing,

a compartment in said housing,

an arcuate resistance element in said housing,

an electrical collector means in said housing,

a movable wiper movably mounted on said collector means and being inmovable electrical contact with said resistance element,

means on said housing limiting the movement of said wiper,

a circular gear means rotatably mounted in said housing and beingoperatively connected to said wiper whereby rotation of said gear meanswill cause said wiper to be moved on said resistance element,

an elongated leadscrew rotatably mounted in said housing and having athreaded portion normally in threaded engagement with said gear meanswhereby rotation of said leadscrew will normally cause the rotation ofsaid gear means,

said gear means being resilient and being capable of being deliected outof engagement with said leadscrew when said leadscrew is continued to ber0- tated after said wiper reaches the limits of its travel,

said gear means being operatively connected to an insulated drivecoupler which is operatively connected to said wiper,

said gear means including a plurality of tabs extending therefrom whichare detachably received by said drive coupler, said wiper including aplurality of tabs extending therefrom which are detachably received bysaid drive coupler,

and a circular spring means positioned between said gear means and saiddrive coupler adapted to yieldably resist the movement of said gearmeans and drive coupler towards each other.

2. In an adjustable potentiometer,

a housing,

a compartment in said housing,

an arcuate resistance element in said housing,

an electrical collector means in said housing,

a movable wiper movably mounted on said collector means and being inmovable electrical contact with said resistance element,

means on said housing limiting the movement of said wiper,

a circular gear means rotatably mounted in said housing and beingoperatively connected to said wiper whereby rotation of said gear meanswill cause said wiper to be moved on said resistance element,

an elongated leadscrew rotatably mounted in said housing and having athreaded portion normally in threaded engagement with said gear meanswhereby rotation of said leadscrew will normally cause the rotation ofsaid gear means,

said gear means being flexible and having peripheral teeth extendingoutwardly therefrom which are adapted to engage the threads of thethreaded portion of said leadscrew,

the exible characteristics of said gear means permitting said gear teethto be deflected and ride over the threads of said leadscrew therebyproviding a ratcheting effect when said leadscrew is `continued to berotated after said wiper reaches the limits of its travel,

said gear means being of metal construction and being operativelyconnected to an insulated drive coupler which is operatively connectedto said wiper,

said gear means including a plurality of tabs extending therefrom whichare detachably received by said drive coupler, said wiper including aplurality of tabs extending therefrom which are detachably received bysaid drive coupler, said drive coupler being positioned between saidgear means and said wiper.

3. In an adjustable potentiometer,

a housing,

a compartment in said housing,

an arcuate resistance element in said housing,

an electrical collector means in said housing,

a movable wiper movably mounted on said collector means and being inmovable electrical contact with said resistance element,

means on said housing limiting the movement of said wiper,

a circular gear means rotatably mounted in said housing and beingoperatively connected to said wiper lwhereby rotation of said' gearmeans will cause said wiper to be moved on said resistance element,

an elongated leadscrew rotatably mounted in said housing and having athreaded portion normally in threaded engagement with said gear meanswhereby rotation of said leadscrew will normally cause the rotation ofsaid -gear means,

said gear means being ilexible and having peripheral teeth extendingoutwardly therefrom which are adapted to engage the threads of thethreaded portions of said leadscrew, y

the tlexible characteristics of said gear means permitting said -gearteeth to be deected and ride over the threads of said leadscrew therebyproviding a ratcheting elect when said leadscrew is continued to berotated after said wiper reaches the limits of its travel,

said housing being comprised of first and second case members detachablysecured together, said resistance element, collector means and saidwiper being mounted in said trst case member, said leadscrew and gearmeans being mounted in said second `case member.

4. In an adjustable potentiometer,

a housing,

a compartment in said housing,

an arcuate resistance element in said housing,

an electrical collector means in said housing,

a movable wiper movably mounted on said collector means and being inmovable electrical contact with said resistance element,

means on said housing limiting the movement of said wiper,

a circular gear means rotatably mounted in said housing and beingoperatively connected to said wiper whereby rotation of said gear meanswill cause said wiper to be moved on said resistance element,

an elongated leadscrew rotatably mounted in said housing and having athreaded portion normally in threaded engagement with said gear meanswhereby rotation of said leadscrew will normally cause the rotation ofsaid gear means,

said gear means being flexible and having peripheral teeth extendingoutwardly therefrom which are adapted to engage the threads of thethreaded portions of said leadscrew,

the ilexible characteristics of said gear means permitting said 4gearteeth to be deflected and ride over the threads of said leadscrewthereby providing a ratcheting effect when said leadscrew is continuedto be rotated after said wiper reaches the limits of its travel,

said gear means including a substantially flat central portion, saidteeth extending outwardly and downwardly into engagement with the upperportion of the threads of said leadscrew, said teeth being deflectedupwardly over said threads when said ratcheting eiect takes place.

5. The potentiometer of claim 4 wherein said leadscrew is maintained insaid housing by a spring means frictionally engaging an annular grooveformed therein r thereby creating torque on the leadscrew so that theleadscrew will maintain its position of adjustment.

References Cited UNITED STATES PATENTS 3,115,614 12/1963 Habeveder338-174 3,124,778 3/1964 Youngbeck 338-131 X 3,242,452. 3/1966 Grunwaldet al. 338-162, X 3,416,119 12/1968 Benthuysen et al. 3355-174 ROBERT K.SHAEFER, Primary Examiner H. l. HOHAUSER, Assistant Examiner U.S. Cl.X.R.

